1. Technical Field
Example embodiments of the present invention generally relate to a semiconductor device and a semiconductor manufacturing method.
2. Background Art
As devices on which photoelectric converting elements are two-dimensionally arranged, solid-state image sensing elements such as complementary metal oxide semiconductor (CMOS) sensors and charge-coupled device (CCD) sensors are known. In particular, a CMOS sensor uses a photodiode as photoelectric converting element, and outputs the signals of the photodiode in a selective manner using metal oxide semiconductor field-effect transistors (MOSFET) provided for each pixel. Due to this configuration, it is possible to build elements such as photoelectric converting elements, output selecting switches provided for each pixel, and peripheral circuits, all in the same substrate by performing known CMOS semiconductor processes. In recent years, processing rules are divided into finer sections, and the size of one pixel is reduced. Accordingly, imaging at higher resolution is progressing.
The photodiode used as photoelectric converting element is formed by PN junction, and a depletion layer is extended by applying reverse bias voltage to the photodiode. The wavelength of light that can be converted into electric charge is determined by the width of the depletion layer. The PN junction is formed in the direction perpendicular to the Si substrate, and the depletion layer extends in the direction of the depth of the substrate. Accordingly, the photoelectric conversion of incident light is performed at a deep portion of the Si substrate. The incident light does not always have an angle of ninety degree but has a variety of angles. For this reason, the electric charge caused by the incident light may be output to the pixel next to the pixel that the light has actually entered. As the size of one pixel is reduced, such confusion about pixel output tends to occur more easily.